Mark Diesen (September 16,1957 -December 9, 2008), World Junior Champ 1976, had a rare combination of positional insight and tactical accuracy. He was well on his way to becoming Grandmaster when he fell off the rails in 1980 due to a common social problem in the USA, narcotics. To put the problem in a global perspective, once German GM Eric Lobron told me he lost innumerable friends of his that he counted as more talented as him at chess to this scourge. To Mark’s credit, he made a complete about-face, ridding himself of the situation that was the total destruction of so many and completing a college degree. He subsequently began working as an engineer in the south (Louisiana and Texas) at various energy companies. He also returned to chess off and on, but never to the serious degree of his ascendancy in the 70s.

He grew up in Potomac Maryland, the next town over from Bethesda and Chevy Chase where I and future IM Steve Odendahl resided. Also nearby were Eugene and John Meyer, Larry Kaufman, Richard Delaune, Robert Eberlein, Allan Savage, Charlie Powell, and many other strong masters. It was quite a concentrated chess area and many hours were spent wiling way the time at blitz with Mark D., me, and Phil (“Flippy”) Goulding. Later in life, both Goulding and Diesen would go on to win the Texas State Championship. I also remember fondly social outings we made to visit Diana Lanni at her job in D.C. and trips over to Larry Kaufman’s chess club in Silver Spring, Maryland.

The apex of Mark’s career was the 1st place finish at the 1976 World Junior Championship. Mark defeated Schussler, Sisniega, and others (drawing Vladimirov and Ftacnik) to take top honors. His coach, GM Lubomir Kavalek, documented this tournament very well in a two-part article, March and April 1977, Chess Life and Review.

Mark's play reminded me of GM Huebner’s style – take what you are given, and display accuracy converting superior positions. He also practiced controlled aggression – attack when the position demands it – this latter quality is reminiscent of GM Portisch. All in all, he struck me as a very “European” player – worlds apart from the piece-sacking barbarians one often runs into at American Swisses. I have found that studying this type of play is quite important to improve tournament results. The “iron logic” of Smyslov, Botvinnik, Petrosian, and so on can be distilled into simply taking what one is given and then putting the opponent in an iron vice of technique. In Diesen’s games, we see this time and again.

Here’s a game where he, at a young age (15), conducted a nice attack versus the 1967 World Junior Champ, Julio Kaplan.

Now let’s see Diesen giving a positional lesson from the black side of this opening to a strong future GM, John Fedorowicz. By and large, Diesen had the edge over his peers in experience and insight in his teen years. He and his main peer, Larry Christiansen, were really super-class juniors.

In this next game from Lone Pine 1977, Diesen swamps young McCambridge’s King’s Indian, gaining space all over the board. One he seizes control of the b-file, Diesen infiltrates, leaving his opponent totally helpless.

In my next and final installment, I will go over more Diesen efforts, including critical games from his triumph at the 1976 World Junior.

Addendum: a nice note from Dr. Eric Moskow:
Source: susanpolgar.blogspot.com Mark, old friend I just heard the crushing news of your loss, I will never forget our game when we were both 5 -0 a dragon in us high school championship, we blitz the moves and you with your genius beat me with your flag hanging, we were the pogo dancers in Sweden in 1976, we talked endlessly over the years on ICC, you were a life long friend even at a distance, The first bright light of the class of 76, even though you were a year ahead of us. I knew you loved your wife and kids who I never met, As a doctor I know life is fragile, your loss rocks my world, its unfortunate that I never really told you what a great memory I hold of our association. Your family will always cherish you and we will play again someday when I can even the score, rest in peace buddy. Eric D Moskow, M.D.

Author’s note: I remember the game referenced by Dr. Moskow very well. At the time, I remember thinking Diesen’s positional experience would carry the day versus someone more booked up. However, things don’t always turn out so cleanly and it was indeed a crazy time scramble.